The invention relates to a method for collecting animals living in or on a water bottom. In particular, the invention relates to a method for collecting crustaceans and shellfish and/or fish living in or on a sea bottom.
As a rule, crustaceans and shellfish living on or in the sea bottom are fished with the aid of trawls which are dragged along the sea bottom. Such trawls are provided with knives reaching into the bottom such that the knives are pulled through the sea bottom with a cutting edge forward. A jet of water is directed at an obtuse angle, in particular approximately at right angles to the direction of movement, approximately vertically to the sea bottom, under high pressure, directly in front of the knives so that the soil of the sea bottom is stirred up and raised. As a result, the crustaceans and shellfish, such as cockles, are disengaged and can move over and/or along the knives. Behind the knives, in the trawl, a collecting basket is arranged in which the crustaceans and shellfish are caught while mud, sand, sediment, undersized shellfish and the like can flow back through the basket. The animals are discharged via a tube system to the craft trawling the trawl.
When using this known method, the sea bottom is agitated in a number of ways which may lead to damage to the environment. For instance, as a result of the water injection and, in particular, the pressure and direction of the jet of water, a relatively large mass of sediment is flushed from the bottom and brought into the water. Moreover, relatively deep, long furrows are made by the knives in the sea bottom. The trawl is heavy so as not to lose contact with the sea bottom. The fact is that as a result of, on the one hand, the trawling force applied to the trawl by the craft and, on the other hand, the force of the jet of water directed approximately vertically, during use, a buoyant force is applied to the trawl which must be compensated by the self-weight of the trawl. This relatively heavy weight of the trawl is borne by runners with which the trawl rests on the sea bottom. These runners cause a further disturbance of the sea bottom, at least of the sediment, growth, marine animals et cetera. When using the trawl on a relatively weak bottom, furrows which are drawn by the trawl in the bottom will be relatively deep, so that the bottom disturbance will be further enhanced.
The invention contemplates a method for collecting animals living in or on a water bottom, wherein the above-mentioned drawbacks have been avoided, at least partly, while maintaining the advantages of the known method. To that end, the method according to the present invention is characterized by a collecting device moved over the bottom, which collecting device is provided with means for moving the animals from or off the water bottom, in particular at least one tine that can penetrate into the bottom and with which said animals can be taken or forced from or off the bottom, while said at least one tine is provided with fluid outlet means through which, under pressure, a fluid, in particular water is forced into the bottom, such that a top layer of the bottom is stirred up and animals living therein or thereon are dislodged, which animals are caught in the collecting device.